1. Field of the Invention
The present invention relates to olefin polymerization catalysts and processes, and more particularly, to novel supported trialkylsilylamide-chromium catalysts, their preparation and use for polymerizing olefins.
2. Description of the Prior Art
A great variety of olefin polymerization catalysts have been developed and used heretofore. Such catalysts can be broadly classified into three groups: the Ziegler catalysts of the type described in Belgium Patent 533,362 issued in 1954; the Phillips Petroleum Company silica supported chromium catalysts as described, for example, in U.S. Pat. Nos. 2,825,721 and 2,846,425 issued in 1958, U.S. Pat. No. 2,951,816 issued in 1960, U.S. Pat. No. 3,887,494 issued in 1975, U.S. Pat. No. 4,119,569 issued in 1978 and U.S. Pat. No. 4,151,122 issued in 1979; and the supported organo-transition metal catalysts of the types described in U.S. Pat. No. 3,709,853 issued in 1973, U.S. Pat. No. 3,806,500 and U.S. Pat. No. 3,840,508 issued in 1974 and U.S. Pat. No. 4,018,707 issued in 1977.
The supported organo-transition metal catalysts include organo-chromium complexes such as bis-(.eta.-cyclopentadienyl) chromium, bis-(.eta..sup.6 -arene) chromium, tri-(.eta..sup.3 -allyl) chromium and tetrakis-(.eta..sup.3 -allyl) dichromium supported on inorganic oxide refractory compounds such as silica, alumina, zirconia and thoria. Another class of supported organo-transition metal catalysts is comprised of tetravalent titanium and zirconium compounds of the formula ML.sub.n X.sub.4--n wherein M is titanium or zirconium, L is --CH.sub.2 C.sub.6 H.sub.5, --CH.sub.2 Si(CH.sub.3).sub.3 or --C.sub.3 H.sub.5, and X is chlorine or bromine supported on inorganic oxides. In the use of the various organo-transition metal catalysts, the particular transition metal, the organic ligands and the inorganic refractory supports used all influence the properties of the resulting polymers.
By the present invention, supported trialkylsilylamidechromium olefin polymerization catalysts are provided, the use of which results in the production of polymers having desired properties.